| With the rapid development of the national economy and the continuous improvement of the people's living standards,the amount of urban garbage and municipal sludge is increasing,and the treatment of the two has become one of the important problems restricting urban development.The synergistic combustion treatment technology of sludge in coal-fired boilers and garbage incinerators has the advantages including harmlessness,reduction,and resource utilization,which is increasingly valued and widely used.In this paper,computational fluid dynamics(CFD)technology was used to carry out numerical simulation research on sludge blending combustion in pulverized coal furnace and sludge blending combustion in garbage incinerator.First,the numerical simulation results were compared with actual operating data to verify the reliability of the model.Second,the effect of blending ratio and sludge moisture content on combustion was studied to be synergistic by analyzing the temperature field distribution,velocity field and NOX distribution under different working conditions,which provide a theoretical basis for collaborative combustion.This paper took a 300 MW four-corner tangential pulverized coal combustion furnace as the research object.The blending combustion process of sludge and pulverized coal in the four-corner tangential pulverized coal furnace was simulated and the influence law on the combustion characteristics was studied at the same time.By comparing the single mixed fraction /PDF model and the double mixed fraction / PDF model,it is found that the double mixed fraction /PDF could describe the difference in the combustion characteristics of sludge and coal powder.With the increase of sludge blending amount and sludge moisture content,the main combustion temperature in the boiler is obviously reduced at least 150 K,and the shape of the four corners is rounded.At the same time,the combustion effect of the fuel becomes worse,and the NOX emissions increase significantly.Comparing with several mixing ratios,it is believed that the mixing ratio of municipal sludge at 40% moisture content is recommended to be controlled within 6%.The blending combustion process of sludge and garbage in the municipal solid waste combustion furnace was studied.Taking a 350 MW urban domestic garbage furnace as an example,Flic and Fluent were used to perform coupling calculation to study the influence of sludge mixing ratio and water content on the operation of garbage furnace.As the blending ratio and the sludge moisture content increases,combustion deteriorates and the temperature in the main combustion zone decreases significantly.Temperature drops more than 150K?Therefore,municipal sludge should be dried,and it is recommended to control the blending ratio within 6%.In order to optimize the sludge blending and incineration in the waste incinerator,the paper took the case of mixing sludge with a water content of 40% and a blending ratio of 5%as an example.The excess air coefficient and the proportion of primary and secondary air distribution was researched,as well as the optimization research on other operating conditions.The numerical simulation results showed that the excess air coefficients of 1.5 and 1.6 are suitable,which can provide sufficient oxygen for the combustion of combustible components.The furnace temperature would not be significantly reduced due to the entry of excessive cold air in order to fully meet the oxygen needs of the primary combustion and secondary combustion of garbage and sludge,the ratio of primary and secondary air is 65:35 or 60:40,because at this ratio combustible gas and air can be fully mixed at the secondary air outlet.Under these circumstances,one-time combustion can also fully dry the water in the garbage sludge. |
PDF Full Text Request